Absence of association between two insertion/deletion coding genetic polymorphisms of TIM-1 gene and asthma in Chinese Han population

Relationship of Severity of Hepatitis A with Polymorphisms in Hepatitis A Virus Cellular Receptor 1 (HAVCR1) Gene

INTRODUCTION AND AIM

HAVCR1 protein is the cellular receptor for hepatitis A virus (HAV). Genetic polymorphism in this gene may alter the outcome of HAV infection. In a previous study, a 6-amino acid insertion (157insMTTTVP) in HAVCR1 gene was associated with more severe disease. We decided to investigate this association further.

MATERIAL AND METHODS

We sequenced exon 4 of the HAVCR1 gene in patients with clinical hepatitis A attending our institution, and a group of healthy controls in a disease-endemic setting in India. Frequencies of different haplotypes of a genomic region with two overlapping insertion-deletion polymorphisms (indels; rs141023871 and rs139041445) were compared between patients and controls, as well as between patients with and without a severe form of disease (liver failure).

RESULTS

The gene had three haplotypes in the region of interest - a short form, an intermediate-form with a 5-amino acid 157insMTTVP insertion and a long-form with a 6-amino acid 157insMTTTVP insertion. The allele frequency (29/150 [19%] vs. 43/146 [29%]; p = ns) and haplotype frequency (29/75 [39%] vs. 39/73 [53%]; p = ns) of the 157insMTTTVP variant were similar in hepatitis A patients and healthy controls (30%). Further, the allele frequency (12/58 [21%] vs. 17/92 [18%]; p = ns) and haplotype frequency (12/29 [41%] vs.17/46 [37%]; p = ns) of the longest variant were also similar in patients with severe and mild disease.

DISCUSSION

In the study population, the 157insMTTTVP variant of HAVCR1 gene was not associated with more severe outcome of HAV infection. Further studies in other populations around the world are needed to assess the relation of this genetic variation with disease outcome.

Associations of TIM-1 Genetic Polymorphisms with Asthma: A Meta-analysis

PURPOSE

Recently, the roles of TIM-1 genetic polymorphisms in asthma have been extensively studied, with conflicting results. Therefore, we performed the present meta-analysis to better assess potential associations of TIM-1 genetic polymorphisms with asthma.

METHODS

Eligible articles were searched in PubMed, Medline, EMBASE, Google Scholar, and CNKI up to December 2016. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to detect any potential associations between TIM-1 genetic polymorphisms and asthma.

RESULTS

A total of 12 articles including 3120 asthma patients and 2825 control subjects were analyzed. The overall and subgroup analyses revealed that TIM-1-416G>C single nucleotide polymorphism was significantly associated with asthma for the Asian population in the codominant (G/G vs. G/C, p = 0.0003, OR 1.86, 95% CI 1.33-2.60) and dominant (G/G vs. G/C + C/C, p < 0.0001, OR 1.94, 95% CI 1.40-2.69) genetic models. Nevertheless, we failed to detect any significant associations between TIM-1-416G>C single nucleotide polymorphism and asthma in Caucasians. Additionally, according to our analyses, TIM-1 5383_5397 insertion/deletion polymorphism was not correlated with asthma in both Asians and Caucasians.

CONCLUSIONS

In conclusion, our findings suggest that TIM-1-416G>C single nucleotide polymorphism is associated with asthma susceptibility for the Asian ethnicity in certain genetic models. However, TIM-1 5383_5397 insertion/deletion polymorphism may not be correlated with the risk of asthma.

Association analysis of -416 G>C polymorphism of T-cell immunoglobulin and mucin domain-1 gene with asthma in Iran

TIM (T-cell immunoglobulin (Ig) and mucin domain)-1, one of the members of TIM family, expresses on Th2 cells and promotes the production of Th2 signature cytokines. This can increase a series of responses in these cells which could be one of the causes of asthma or asthma-related phenotypes. The aim of this study was to investigate whether a TIM-1 promoter single nucleotide polymorphism (SNP), -416 G>C, is associated with asthma in Iranian population. In this case-control study, existence of the -416 G>C polymorphism was assessed using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) in 300 patients with asthma (97 atopic, 203 nonatopic) and 309 healthy volunteers. Additionally, the relationship between these polymorphism genotypes and total serum IgE levels in this Iranian population was evaluated. We discovered a significant association between the -416 G>C polymorphism and atopic asthma susceptibility in the population, but this SNP showed no connection with nonatopic asthma (P < 0.05). However, our results showed significant relation between this polymorphism and serum IgE level (P < 0.05). Our results suggest that -416 G>C polymorphism in TIM-1 gene could be a predisposing factor for atopic asthma in Iranian population, and CC genotype of this SNP can be associated with increased level of IgE in patients with asthma in the same population.

Pooled-analysis of the association between TIM-1 5383_5397 insertion/deletion polymorphism and asthma susceptibility

The T cell immunoglobulin (Ig) domain and mucin domain 1 (TIM-1) gene play an important role in pathogenesis of asthma. We investigate the association between the TIM-1 5383_5397 insertion/deletion polymorphism (rs45623443) and the risk of asthma in an asthma case-control study, and added these data to a literature-based meta-analysis. The TIM-1 5383_5397 insertion/deletion polymorphism genotype was analyzed in 156 asthma patients and 162 healthy subjects from Han Chinese population. We combined our data with that from previously published studies and performed a meta-analysis to evaluate the effect of the gene. Through regression model, we found no significant association for TIM-1 5383_5397 insertion/deletion polymorphism in our cohort. Meta-analysis, comprising a total of 1,577 asthma cases and 1,781 controls, revealed that no significant association between and asthma susceptibility was observed (OR = 0.99, 95 % CI = 0.83-1.20 for Ins vs. Del; OR = 1.01, 95 % CI = 0.74-1.37 for Ins/Ins vs. Ins/Del + Del/Del; OR = 0.96, 95 % CI = 0.78-1.18 for Ins/Ins + Ins/Del vs. Del/Del). The present meta-analysis suggested that TIM-1 5383_5397 insertion/deletion polymorphism may not substantially contribute to asthma susceptibility. However, gene-gene and gene-environment interaction effects and other considerations involving this polymorphism may exit.

Association of Hepatitis A exposure and TIM-1 with childhood allergic asthma

BACKGROUND

Hepatitis A virus (HAV) receptor (TIM-1) polymorphism plays an important role in asthma and autoimmune diseases. Objective. To analyze the association of TIM-1 polymorphism and HAV infection with childhood allergic asthma in Southwest China.

METHODS

TIM-1 exon 4 (157insMTTTVP) and two polymorphism loci, -416G>C and -1454G>A, in the HAV receptor promoter region were studied. Polymerase chain reaction (PCR) was used to test the genotypes of three polymorphism loci among 579 cases of asthma and 524 controls. The HAV infection status was determined in a case-control study with stratified analysis.

RESULTS

HAV exposure associated with childhood allergic asthma in the study population was compared with controls (odds ratio (OR) = 0.181, 95% confidence interval (CI) 0.126-0.260, p < .001). The -416G>C polymorphism was associated with asthma (OR = 1.384, 95% CI 1.148-1.669, p < .001), but the insertion variant 157delMTTTVP of exon 4 and the -1454G>A polymorphism were not.

CONCLUSION

Our results indicated that the -416G>C polymorphism of the TIM-1 gene is associated with childhood allergic asthma, providing a better understanding of the pathogenesis of the allergic asthma among children aged below 15 years in Southwest China.

Polymorphisms of the TIM-1 gene are associated with rheumatoid arthritis in the Chinese Hui minority ethnic population

The T-cell immunoglobulin and mucin domain 1 (TIM-1) is known to be associated with susceptibility to rheumatoid arthritis (RA). We investigated the association of four single-nucleotide polymorphisms (SNPs) in the promoter region of the TIM-1 gene with susceptibility to RA in a Chinese Hui ethnic minority group. Using RFLP or sequence specific primer-PCR, 118 RA patients and 118 non-arthritis control individuals were analyzed for the -1637A>G, -1454G>A, -416G>C, and -232A>G SNPs in the TIM-1 gene. The polymorphisms -232A>G and -1637A>G in the promoter region of TIM-1 were found to be associated with susceptibility to the RA gene in the Hui population, while -416G>C and -1454G>A SNPs were not. Of these, the polymorphism of -232A>G is inconsistent with that found in a Korean population, suggesting that genetic variations of the TIM-1 gene contribute to RA susceptibility in different ways among different populations. Based on haplotype analysis, individuals with haplotypes AGCA (Χ(2) = 22.0, P < 0.01, OR (95%CI) >1), AGCG (Χ(2) = 18.16, P < 0.01, OR (95%CI) >1) and AGGA (Χ(2) = 5.58, P < 0.05, OR (95%CI) >1) are at risk to develop RA in the Chinese Hui population; those with the GAGA (Χ(2) = 7.44, P < 0.01, OR (95%CI) <1) haplotype may have a decreased likelihood of RA. GGCA and GGCG are more common in both RA and non-RA subjects. We conclude that -1637A>G and -232A>G polymorphisms of TIM-1 are associated with susceptibility to RA in the Chinese Hui population.

TIM polymorphisms--genetics and function

The transmembrane immunoglobulin and mucin domain (TIM) family was identified more than a decade ago. Although the founding member of the family was first described in a rat model of ischemia-reperfusion injury, much of the recent interest in the TIM family members has focused on their potential roles in immunity. There are now a large number of genetic studies that have investigated the possible association of various TIM1 and TIM3 polymorphisms with different diseases. Here, we review this body of literature, and highlight some of the most interesting studies.

Polymorphisms of the TIM-1 and TIM-3 genes are not associated with systemic lupus erythematosus in a Chinese population

Systemic lupus erythematosus (SLE) is a prototypic systemic autoimmune diseases, which affects multiple organ systems such as kidney. The imbalance of T-helper 1 (Th1)/Th2 cells is critical in the pathogenesis of SLE. The T-cell immunoglobulin mucin (TIM) proteins comprise a family of cell surface molecules expressed on T cells that regulate Th1- and Th2-cell-mediated immunity. Recent work has found increased expression of TIM-1 and TIM-3 ligand (galactin-9) mRNA in SLE patients and implied that TIM proteins might be involved in the pathogenesis of SLE. In this study, genotyping of single-nucleotide polymorphisms (SNPs) was performed for TIM-1 (rs1501909 and rs12522248) and TIM-3 (rs9313439 and rs10515746) in 202 SLE patients and 217 healthy individuals in a Chinese population. Results showed no significant differences existed between the patients with SLE and the controls as well as SLE patients with nephritis and those without nephritis, in all four SNPs. The findings suggest that the polymorphisms of TIM gene family might not contribute to SLE susceptibility in the Chinese population. However, it should be noted that the statistical power of our study is relatively low, which likely did not have adequate power to detect the actual correlation between the selected SNPs and SLE susceptibility; moreover, we cannot discard a possible association of other variants within the region covering TIM with SLE as a genetic risk factor, with larger samples in different populations.

Two polymorphisms in the TIM-4 gene are associated with asthma in a Chinese Han population

The gene family of the T cell immunoglobulin and mucin domain (TIM) proteins encodes cell surface receptors that are involved in the regulation of Th1- and Th2-cell-mediated immunity. TIM-1 gene has been found to be associated with asthma in several populations. TIM-4, the natural ligand for TIM-1, may influence the susceptility to asthma.To investigate the association of the TIM-4 gene polymorphisms with asthma in a Chinese Han population. Three single nucleotide polymorphisms (SNPs) in TIM-4 gene, rs6882076, rs12658558 and rs4702747, were genotyped in 551 unrelated asthma patients and 549 healthy controls. We found that two SNPs of the TIM-4 gene, rs6882076 and rs4702747, were associated with asthma susceptibility in our study population (with P-values = 0.009 and 0.005 respectively). No association was observed between asthma and rs12658558. Our results suggest that TIM-4 gene polymorphisms are associated with asthma in a Chinese Han population.

TIM genes: a family of cell surface phosphatidylserine receptors that regulate innate and adaptive immunity

The TIM (T cell/transmembrane, immunoglobulin, and mucin) gene family plays a critical role in regulating immune responses, including allergy, asthma, transplant tolerance, autoimmunity, and the response to viral infections. The unique structure of TIM immunoglobulin variable region domains allows highly specific recognition of phosphatidylserine (PtdSer), exposed on the surface of apoptotic cells. TIM-1, TIM-3, and TIM-4 all recognize PtdSer but differ in expression, suggesting that they have distinct functions in regulating immune responses. TIM-1, an important susceptibility gene for asthma and allergy, is preferentially expressed on T-helper 2 (Th2) cells and functions as a potent costimulatory molecule for T-cell activation. TIM-3 is preferentially expressed on Th1 and Tc1 cells, and generates an inhibitory signal resulting in apoptosis of Th1 and Tc1 cells. TIM-3 is also expressed on some dendritic cells and can mediate phagocytosis of apoptotic cells and cross-presentation of antigen. In contrast, TIM-4 is exclusively expressed on antigen-presenting cells, where it mediates phagocytosis of apoptotic cells and plays an important role in maintaining tolerance. TIM molecules thus provide a functional repertoire for recognition of apoptotic cells, which determines whether apoptotic cell recognition leads to immune activation or tolerance, depending on the TIM molecule engaged and the cell type on which it is expressed.

TIM genes: a family of cell surface phosphatidylserine receptors that regulate innate and adaptive immunity

The TIM (T cell/transmembrane, immunoglobulin, and mucin) gene family plays a critical role in regulating immune responses, including allergy, asthma, transplant tolerance, autoimmunity, and the response to viral infections. The unique structure of TIM immunoglobulin variable region domains allows highly specific recognition of phosphatidylserine (PtdSer), exposed on the surface of apoptotic cells. TIM-1, TIM-3, and TIM-4 all recognize PtdSer but differ in expression, suggesting that they have distinct functions in regulating immune responses. TIM-1, an important susceptibility gene for asthma and allergy, is preferentially expressed on T-helper 2 (Th2) cells and functions as a potent costimulatory molecule for T-cell activation. TIM-3 is preferentially expressed on Th1 and Tc1 cells, and generates an inhibitory signal resulting in apoptosis of Th1 and Tc1 cells. TIM-3 is also expressed on some dendritic cells and can mediate phagocytosis of apoptotic cells and cross-presentation of antigen. In contrast, TIM-4 is exclusively expressed on antigen-presenting cells, where it mediates phagocytosis of apoptotic cells and plays an important role in maintaining tolerance. TIM molecules thus provide a functional repertoire for recognition of apoptotic cells, which determines whether apoptotic cell recognition leads to immune activation or tolerance, depending on the TIM molecule engaged and the cell type on which it is expressed.

Identification of HAVCR1 gene haplotypes associated with mRNA expression levels and susceptibility to autoimmune diseases

Human HAVCR1 gene maps on 5q33.2, a region linked with susceptibility to allergic and autoimmune diseases. The aims of the present study were to define the haplotypes of HAVCR1 gene taking into account both HapMap Project SNP haplotypes and exon 4 variants, to investigate a possible relationship between these haplotypes and mRNA expression levels, and to assess whether HAVCR1 gene is involved in susceptibility to rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Genotyping of three ins/del variants in the exon 4 was performed by fragment length analysis. Five tag SNPs genotypes and mRNA levels were determined using TaqMan assays. We defined four major haplotypes in our population: the two major haplotypes (named haplotypes A and B) bear both the 5383_5397del variant and the two most common SNP sets found in the CEU population. Quantification analysis revealed that genotype B/B had the highest median of mRNA expression levels (vs. BX + XX, p < 0.0001). Additionally, frequency of the genotype BB was significantly higher in RA patients than in controls (12.3 vs. 5.9% in controls, p = 0.0046, p (c) = 0.014, OR = 2.23, 95% CI 1.23-4.10). Our results support a relationship between HAVCR1 haplotypes and mRNA expression levels, and suggest an association of this gene with autoimmune diseases.

Association study between vitamin D receptor gene polymorphisms and asthma in the Chinese Han population: a case-control study

BACKGROUND

Modulation of the immune system is one of the principal roles of Vitamin D, for which the effects are exerted via the vitamin D receptor (VDR). Importantly, variants in the VDR gene have been susceptible in the past to raise the risk of asthma in several populations. These effects of VDR allelic markers remain speculative in the Chinese Han population.

RESULTS

A case-control study of 1090 individuals including 567 asthmatic patients was realized on five SNPs within the VDR gene. Only rs7975232 (ApaI) marker showed a significant association with asthma (P = 0.009). Haplotype analysis of the five VDR polymorphisms showed a significant association with asthma (global-p value = 0.012).

CONCLUSION

Although the susceptibility of VDR gene variants with asthma could not be confirmed for all SNPs tested in this study, the significant association obtained for rs7975232 provides evidence for a previously unknown report about the Chinese Han population and may raise the susceptibility of VDR to be a candidate gene for asthma.

The role of the T-cell costimulatory molecule Tim-1 in the immune response

Upon encountering antigen, CD4+ T-cells become activated and can differentiate into subsets with distinct functional characteristics. One of these subsets is the Th2 cell, which generates large amounts of interleukin (IL)-4, -5, -10 and -13 in response to a subsequent encounter with antigen. In the context of a protective immune response, Th2 cells promote immune cell activation, antibody production, and inflammatory responses that help clear infections. However, aberrant responses by Th2 cells can lead to debilitating allergic diseases such as asthma. Thus, a reasonable approach toward gaining novel insights into immunity and allergic disease is to define the mechanisms that control Th2 cell differentiation and mature Th2 cell function. Recent work suggests that a protein called Tim-1 (T-cell immunoglobulin and mucin protein-1) is expressed on CD4+ T-cells and plays a central role in regulating Th2 responses. Genetic analysis has linked polymorphisms in the human TIM1 gene to susceptibility to allergic disease, while studies involving mice have shown that ligation of Tim-1 promotes CD4+ T-cell activation. The signal transduction pathways downstream of Tim-1 are a relatively unexplored area. Continued study will undoubtedly reveal novel insights regarding the relationships between Tim-1, Th2 responses, and allergic disease.

A functional polymorphism in the TIM-1 gene is associated with asthma in a Chinese Han population

BACKGROUND

TIM-1, a member of the T cell immunoglobulin and mucin domain (TIM) gene family was implicated as an asthma susceptibility gene in previous studies. TIM-1 is selectively expressed on activated CD4+ T cells and its expression is sustained preferentially on T helper type 2 (Th2) cells, which suggests that TIM-1 is associated with T cell differentiation and the development of Th2-biased immune response.

METHODS

In order to evaluate the effects of the promoter polymorphism in the TIM-1 gene on asthma susceptibility in a Chinese Han population, 2 promoter polymorphisms, -416G>C and -1454G>A, from 2 alternative promoter regions, were genotyped in 409 unrelated asthma patients and 305 healthy controls by using polymerase chain reaction and restriction fragment length polymorphism. Also, we analyzed the functional significance of -416G>C using the luciferase reporter gene assay.

RESULTS

We found that -416G>C was associated with asthma susceptibility in our study population (chi2 = 9.88, p = 0.002, odds ratio 1.41, 95% confidence interval 1.14-1.75). No statistically significant difference in the distribution of genotype and allele frequency of the -1454G>A site was observed. The -416G>C substitution increased the transcriptional activity of the TIM-1 gene.

CONCLUSION

Our findings suggest that the -416G>C variation site in the human TIM-1 promoter region is associated with asthma susceptibility in a Chinese Han population.